Genetic Info. Source
 

Genetic Information Source for
Australian Shepherd Breeders and Owners

This page will expand as I uncover more information.  For starters, I'd like to direct all readers to the following web site: Alaskan Malamute Health - Breeding for Health.  This is by FAR the best web site I've found addressing multiple concerns about breeding dogs for better genetic health.  Included are interviews with canine geneticists and veterinarians Drs. Bell, Padgett and Willis - all notable authors and researchers.  Also, check out the links on genetic risk assessment, breeding strategies, pedigrees and any of the genetic disorders listed that may be of special interest to you.

Genetics can be vastly complicated and answers are often elusive.  Dogs have more chromosomes than any other animal. It is not always possible to select against a particular genetic disease without sacrificing other, desirable components.  Dogs, genetically, come as a whole package.  For further information on dog breeding and canine genetics, I recommend the following books (available through amazon.com or dogwise.com):

• "Dog Breeding as a Fine Art", by Amy Fernandez (Ltd. Editions Media, Inc.)
• "Control of Canine Genetic Diseases", by George Padgett, DVM (Howell Book House)

Genes can be inherited in one of several ways - they can be dominant (only takes one gene to produce the condition), recessive (takes a pair), or polygenic (takes many).  It is not altogether difficult to select against disorders known to be inherited by simple recessive or dominant means.  However, many of the undesirable traits that breeders are plagued by are polygenic in nature, meaning they are controlled by many genes.  Their expression is also influenced by environmental factors. Hip dysplasia (HD), for example, is controlled by multiple genes.   With polygenic disorders, the genes needed to predispose an individual to a condition may lie latent for generations until the right combination of two dogs comes together.  As with HD, the best thing that breeders can do is collect lateral pedigree information by interviewing (in a non-confrontational way) owners of related dogs and ancestors regarding the incidence (%) of the condition in their lines AND staying in close communication with the buyers of their litters so that they can be informed if any health concerns appear.  

With polygenic traits, it is the percentage of occurrence of the condition within any given cross that provides the most information on heritability, not how many ancestors how far back in a pedigree were problem-free.  When the rate of incidence far exceeds what is normal for the breed, breeders must then make a decision about whether or not to continue to use animals that produce such problems, as well as siblings of affected dogs.  The exemplary qualities passed on by those animals and the absence or presence of other diseases must also be considered.  Condemning an entire line or kennel or any dog for producing a problem is to overlook their positive traits and contributions to the breed.  Yes, we should be conscientious about which dogs we choose to breed, sometimes wisely electing to remove dogs from a breeding program, but we also have to be realistic about how much control we have over some situations. Furthermore, we must always keep an eye towards producing the best dogs overall - health-wise, physically and temperamentally - that we can.

Education is paramount to understanding and making wise decisions.  Although genetic testing is slowly becoming more and more available for specific genes, it is a science still in its infancy.  We can't yet sift out all the bad genes while keeping all the good ones.  

When it comes to specific genetic disorders, we should seek to do the following:

• Learn the mode of inheritance of that disorder.
• Figure out the rate (%) at which it has occurred in a cross (how many siblings are affected?). 
• Trace where in a pedigree the condition may be originating from, if known.  Remember, dams as well as sires can be carriers - in other words, it usually takes two to tango.
• Question how thoroughly were any affected dogs tested in relation to the disease and how reliable was the diagnosis?  Misdiagnosis can turn an entire breeding program upside down.  I am aware of breeders who have neutered dogs they believed to be affected by a specific disorder that they later found out were not.
• Ask how severely the dog in question is affected.  Has the disease meant an early euthanasia or is the dog still functioning relatively normally and expected to live a full life?  Is the condition manageable through nutrition, medication or monitoring?  
• What was the age of onset of the condition?  It becomes harder to select against disorders that appear later in life.

Too often we hone in on a single genetic disorder at the expense of other good traits and genetic diversity.  In effect, we run away from what we are trying to avoid and in so doing we lose sight of what we are trying to gain or improve upon.  Breeding should never be solely about avoiding the negatives, it should be about keeping the positive traits that make the breed or a specific line extraordinary.  Below, I've selected the most informative and objective sites that I could find.   

All the Best,

Gemi

Please notify us of any broken links you come across so we can keep this updated.  Thanks!

Breeding:

• The Ins and Outs of Pedigree Analysis, Genetic Diversity, and Genetic Disease Control - by Jerold S. Bell, D.V.M.

• The Genetic Gamble - an article from Today's Breeder with an excellent overview on canine genetics, including modes of inheritance and breeding advice, with quotes from notable canine geneticists.  

Autoimmune Disorders:

• Canine pemphigus vulgaris

• International Phemphigus Foundation

• Skin Diseases - Allergic, autoimmune, infectious and parasitic skin diseases.

• Lupus

Epilepsy:

• Canine Epilepsy - by Dr. Todd Woods, MD.  A thorough article by a neurologist and long-time breeder on the multiple modes of inheritance for canine epilepsy and how to approach breeding decisions.
• Canine Epilepsy Network - Information on canine epilepsy, all-breed research and sample submission.
• Ivermectin Sensitivity Test

Eye Diseases:

• Cataracts - Modes of inheritance, breeds affected.
• CERF Diagnostic Spotlight - By Canine Eye Registry Foundation.  An explanation of various eye disorders in dogs, including: Progressive Retinal Atrophy, Cataracts, Collie Eye Anomoly and Persistent Pupillary Membranes.
• CERF - Canine Eye Registration Foundation.  Discusses the importance of eye exams, eye problems and maintains a database.
• Eye diseases - Details on most eye diseases and their treatment from Animal Eye Care.

General:

• Genetics Glossary - Comprehensive list of genetic terms.
• The Canine Diversity Project - A vast array of information on canine health and genetics.

Hip Dysplasia:

• OFA - Orthopedic Foundation for Animals.  Explains hip dysplasia, gives breeding guidelines and also maintains a database by which you can search for ratings by kennel name or registered name of a dog.
• PennHIP - Article by Fred Lanting.
• PennHIP - Interview with Dr. Gail Smith.